Rainbow Reef is actually a point scoring puzzle app. The object is to swipe/direct the swimming sea creatures to the matching colored circles. See the green seaweed? Those are blocks - fish can't swim through them.
The game ends, for example, when a red fish goes into a yellow circle.
Rainbow Reef starts the game easy. After 5 or 6 levels, they start to get tough.
The author is Jacqueline Hudepohl and it's nice to see puzzle app games from women. I think kids would like this.